text:
Why do evacuations result in so many injuries?
Evacuations often end in several minor and sometimes serious injuries, why is this? What are the most common causes? I've never done it, but I struggle to imagine how sliding down an inflatable can cause so many issues.

Take 150 random people of all ages and medical conditions from a shopping mall out into the parking lot and put them on a playground slide and see how things go.

What Steve said. Like, me, I'm gonna be fine hurling myself down even a fairly steep slide with a bad landing site at a moment's notice. Put my 60-something mother on there, I'm not so sure. My aunt, who already has physical problems, is almost certain to be injured on it even given plenty of time to prepare.

Dozens to hundreds of animals suddenly panicked and herded towards traffic choke points. In nature we call this a stampede. For humans, its an evacuation.

@DavidS: animals don't obstruct the stampede by trying to bring their carry-on with them.

@DarthPseudonym: even professional athletes get sometimes hurt when warming up or doing other non-intense movements.

In most martial arts and gymnastics you are generally 'taught' how to fall and frequently an ongoing practice.

Evacuation is intended to happen within 90 seconds. For comparison, have you ever measured how looong it takes for everybody to leave the plane when there is no problem at all, the plane sits comfortably at the finger and everybody is extremely eager to get out (e.g., because the landing was delayed) and even if hardly anybody has hand luggage? Heck, it typically takes 5 minutes until the person standing in the aisle and blocking me from getting up is able to move a single step forward ...

The exprerience is far from playground slides. The evacation slides are very slippery and thus quick so the landing is not necessarily graceful. Also as hundreds of passengers are required to evacuate within very short time frame, the slides are filled with people bouncing to each other. Typical injuries include fractured ankles and collarbones. Also in case of fire and smoke events there are respiratory injuries due to smoke inhalation.
Here is a video about evacuation certification

One of the most challenging tasks during A380 development was to design the upper deck slides such that they would stay stiff even when loaded with lots of people on them and to limit the speed at which people arrive on the ground. +1

I'd also point out that the landing site on a playground slide is generally clear and flat, and likely sand or pea gravel to absorb some impact. An airline slide will dump you out onto tarmac or smooth grass if you're lucky, but there's no guarantees it won't be uneven and/or rocky. And even tarmac can take the skin off your calves if you aren't ready for it.

PANIC. Note there are many injuries also when fire alarm and evacuation is performed in buildings, plazas, and concerts. Crow management is difficult. Close spaces creates more panic (so same problems with less people).

About 5.45 on that video, if you keep a close eye on the left hand slide, you'll see one of the cabin crew - the very last to evacuate - having a fairly violent tumble.

I just assumed that it's very similar to the UK sport of cheese rolling.

@PeterKämpf I also remember reading there was a speculation that people would not dare to slide down from the upper deck.

There is no valid answer for this question unless you take a specific example of evacuation with injuries.
The only obvious factor to injuries is scare and loss of composure. Of course some persons are more exposed than other when dealing with fast and unusual actions, including the elderly and the already injured.

But for a person in good fit an emergency slide is not dangerous by itself. You could use it a whole day long for amusement, and you wouldn't be injured.
Each evacuation is a specific case, passengers will be confronted to different dangers and hazards in different evacuation types, e.g.:

On the flat runway stop area after a slight runway excursion.

After a water landing.

While there is already a fire in the cabin

After a crash in mountainous area, etc.

There are usually no injuries in an evacuation test in the hangar of the manufacturer with people, who are manufacturer's workers relatives, prepared for the evacuation without any baggage and with no actual emergency. If you know your life isn't threatened you are more willing to take care of what you do and do to others.
It also depends on the nationality of the passengers. There are citizen from several countries that are used to be very patient and disciplined, even when their life is threatened. This is also true for some professions. Evacuating a military aircraft may be different from evacuating a civilian aircraft. On the other hand in some countries, e.g. in my own country, more people are rather selfish and know better than crew members about what to do and where to put priorities.
People with luggage (in spite of being told not to take them), people rushing and pushing other persons waiting to leave the plane, people with babies in their hands, etc, are potentially adding danger for themselves or for others.
Is that different from what you would see when a building is in fire and residents use a simple stair to evacuate it? Would that be different using a simple slide at the pool under the pressure of an emergency?

Untrained people are thrown into a sudden, confusing, dangerous, situation they're not prepared for.
Of course there are going to be injuries. This is not specific to aircraft evacuations, evacuations of office buildings (even practice evacuations, regularly lead to injuries. So do evacuations of trains, buses, ships, anywhere where a group of people without prior training is told to quickly leave the area.
Throw in the already hazardous (even to trained staff) surroundings and accidents become even more likely (think the case some years ago where an evacuating passenger got out of the aircraft uninjured and then ran headlong into an approaching fire truck and was killed for example).

I think you're thinking of this https://edition.cnn.com/2014/01/15/us/asiana-crash-new-video/index.html - she didn't run headlong into a firetruck, quite the opposite - the firetruck ploughed headlong into her when she was already unconscious on the ground!

Another point to consider is that if passengers were never injured in evacuations, that would strongly suggest that evacuation procedures are slower than they should be to maximize the number of people who escape alive.

@Jamiec and some reports suggested the fire crew laughed about it...

The only purpose of evacuation is getting as much people out alive in shortest time possible. If they can walk afterwards, it is considered an optional extra.
During evacuation you want to move people from possibly lethal location to much safer location. The focus is on survival, not comfort. Being in a posibly lethal position is very stressful and very few people can handle that even after many trainings.
Adding stressed crowd to rush and unusual physical activity without prior warning assures little nuisances like dislocated joint, broken bone or scratch.

If most couldn't walk afterwards, you'd have a problem clearing the bottom.  The acceptable rate of crippling injuries has to be fairly low to allow people to reach safety (right next to a burning plane isn't safety)


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Is the seat-belt sign activation when a pilot goes to the lavatory standard procedure?
Yesterday, I took an inter-European commercial flight with a popular budget airline. Before take-off, the captain announced that the First Officer would be taking the entire flight today.
During the middle of the approximately 2 hour cruise, the seat-belt sign came on. The flight attendant, who was next to me at the time, quickly turned to look at the front of the cabin.
The captain came out of the cockpit, a flight attendant took his place and locked the door behind him, he spoke over the PA system and asked everyone to fasten their seat-belts. A couple of people stayed up and he firmly told them, again over the PA, to sit down and fasten their seat belts.
Despite largely overcoming my fear of flying recently, I was slightly alarmed at this point, so I asked the flight attendant if we were expecting some turbulence. He told me that no, we weren't and that the seat-belt was only because the captain needed to use the restroom.
Sure enough the captain used the restroom, came out, re-entered the cockpit and a few minutes later turned the light off.
My question -  is this standard procedure or is it likely the flight attendant was giving me the 'passenger friendly' version of the story? I have since wondered if it was the FOs first 'solo' flight and if that might have been related.

@ymb1 I want to know if this is the normal procedure for commercial airlines. It's a simple question I suppose, I'm just curious.

"the captain announced that the First Officer would be taking the entire flight" That would hardly be unusual. "wondered if it was the FOs first 'solo' flight" Not sure what you mean by "solo" here, but if you mean in the sense of flying the entire time without assistance, as in the typical one-pilot-certified GA aircraft, then definitely no. That type of flying doesn't exist in large jet passenger operations, possibly short of some very specific emergency situations (see for example British Airways 5390).

@aCVn Meh, who knows - I thought maybe he was taking the flight unaided either to improve his skills or just for fun / to relieve boredom or the captain was tired.

@Cloud Virtually all airliners are multi-crew airplanes, meaning that at least the required number of crew (typically 2 pilots these days, but also included flight engineer and/or navigator in the past) must be on duty. Typically, though, the work is divided between "pilot flying" (the one actually manipulating the flight controls) and "pilot-not-flying" (who is reading checklists, working radios, etc.) It's normal for the Captain and FO to alternate segments for who is PF and who is PNF, particularly on short-haul flights. On your flight, the FO was PF.

Not sure if it is a standard procedure but on AirAsia they put the meanest, musculine cabin crew across the cabin with arm stretch. I won’t challenge that.

In the US they do very similar theater when a pilot needs to relieve himself. There is an announcement that nobody is allowed to come forward, and grim looking flight attendants are blocking the aisles with coffee trolleys. The details surely depend on the airline.
Each of these procedures goes back to some bad incident. The cockpit doors are locked since 9/11. Since Germanwings 9525 (PIC on toilet, co-pilot had a death wish, cockpit door locked), a flight attendant has to replace the pilot in the cockpit. I'm not sure if there was an incident calling for body-guarding a pilot outside of the cockpit, but maybe someone can comment.
Even though it is much more likely to get killed by your angry spouse or just falling down the stairs at home, security procedure theater is in fashion, and it is just getting worse and worse. Yes, it is very plausible that the seat-belt sign activation in your flight was standard procedure to ensure that the PIC could pee in peace.

This photo of Thomas Cook Airlines (UK) is courtesy of TripAdvisor
Some similar reports found in the depth of the internet:

boards.ie in August 2013:

Noticed this last night on a Ryanair flight.
Internal phone call to stewardess was then followed by the fasten seat
  belt sign going on. We were forced to sit down with a by then crying
  baby (who had been just about dozing off being rocked whilst standing
  up) Once we were all sat down cockpit door opens, one of the pilots
  exits and was replaced by an air hostess in the cockpit. He visits the
  loo, comes back out, rings in, door opens, swaps with the air hostess
  and then the lights go back off. Not a hint of turbulence during the
  time period involved. [...]

flyertalk.com in August 2008:

In the middle of a flight today from LAX-ORD, the seat belt sign was
  turned on and the pilot or co-pilot came out of the cockpit to use the
  bathroom. As soon as the pilot went back into the cockpit, the seat
  belt sign was turned off. It was perfectly smooth throughout this
  portion of the flight, so it was obvious that the seat belt sign was
  turned on just for the pilot to use the facilities. [...]

PIP has just gotten a new meaning...

I've never seen an airline in the US turn the seat-belt sign on in such situations. Blocking the forward galley, yes, but never "the entire plane must sit down until the captain's done with the restroom."

FAA had the two people in cockpit rule long before the Germanwings crash, it was due to potential incapacitation during a depressurization. And EASA changed their mind about that rule, leading to most European airlines rolling it back.

@ZachLipton Cloud's flight was in EU, and they didn't use the juice cart.

This is a truly comical answer. Two people in the cockpit rule has been around worldwide since well before Germanwings, and there have been plenty of incidents of people trying to jump the cockpit during events that require opening the cockpit door (meals, water, bathroom break on a long flight, etc.) Literally nobody cares about angry spouses or stairs when combing a hillside for human remains.

@JuanJimenez May I take that as a compliment? 2 ppl rule existed before GW9525 in the US, but not in the EU. (And  user71659  is right that most if not all EU airlines have abandoned it during 2017-18). My point about the angry spouses is that our perception of risk and death cause probabilities is very skewed. IMHO we should care much less about terrorism, and much more about more probable problems. IMHO the locked cockpit door creates much more threats than it prevents.

@bogl The "two persons in the cockpit rule" has not been abandoned by all US airlines. To this day I still see it applied, and for good reason. I've seen some of the more foolish articles written by paranoid people who say they are more worried about the mental health of pilots than pax. That is patently absurd. The number of incidents in aircraft involving pax far outnumber the ones involving pilots, and pax don't have to renew medical certificates every 12 or 6 months depending on their age to get in an airplane.

@JuanJimenez - User bogl said the two person rule had been abandoned by "most if not all EU airlines", not US. If you look at user71659's comment you can find more information about the EU airlines' abandonment of the rule per the EASA's recommendation.

I've flown quite often and never seen this happen. Is it that some models of planes have bathrooms for the flight crew that don't require this? Or have I just not noticed?

@RoddyoftheFrozenPeas I flew Air France to Boston earlier this year and the rule was applied. Emphasis on EASA's "recommendation."

@AzorAhai What airline and region do you travel usually?

I'd hesitate to call this "security theatre".  Unlike e.g. banning liquids and other very narrow defences that are easily worked around and waste huge amounts of time and resources, this seems like a reasonable (if heavy-handed) procedure to effectively mitigate plausible but unlikely threats to the safety of the flight.  It's not like it slows anyone down in the big picture; the plane still arrives at the same time, and it doesn't add extra weight or cost to anything.

@bogl I don't travel for work or anything, and probably not nearly as much as people here, but enough I would have thought I've seen this happen? Continental US, anyone really, but Alaska most frequently.

@PeterCordes What is wrong with closing the galley curtain and doing the exchange ceremony discretely? The trolley parade is over the top, ineffective, and an offense to respectable passengers. Just my opinion.

@bogl Because that's security by obscurity. "Respectable passengers" would rather not have the cockpit rushed by suicidal (or drunk!) idiots.  Of course the vast majority of passengers are not going to do this, but it only takes one to really spoil everyone's day.  If the only downside is that easily-offended passengers are offended, then frankly they can either suck it up or not travel.

This is standard procedure when a pilot needs to use the lavatory (bathroom).

The area near the front lavatory is blocked off by cabin crew, so you cannot get into this area.
The pilot unlocks the cockpit door, steps out, and goes into the lav.
a cabin crew member takes his place, and the cockpit door is closed.
reverse steps 1-3.

Why step 1?  To avoid a rush on the cockpit by malefactors. This change occurred after 9/11 -- prior to that, "The Book" on dealing with hijackers said to give them cockpit access, because they'd never done anything bad with it.
Why step 3?  So the remaining pilot is not alone in the cockpit. In some airlines, this has been standard practice for years, because of fear of accidents suspected to be solo pilots making a horrible mistake.  This was strongly disputed by the unions and doubters, and there wasn't data-recorder data. There was after a burst of them: 2013 LAM 470 (data recovered), 2014 Malaysian 370 (suspected; no data) and 2015 Germanwings 9525 (data recovered). Nobody could deny it anymore, and everyone applied the rule.
Interestingly, Tom Clancy predicted both 9/11 and the emotionally distraught solo pilot, in his 1994 book Debt of Honor.
By the way, the reason the copilot took the flight was that he needs a certain number of takeoffs, landings and hours of flight to keep his skills up.

"a cabin crew member takes his place, and the cockpit door is closed." - the two-person rule was rescinded by many airlines in 2017. And anecdotally, on all of my recent US domestic flights where I've seen one of the pilots leave the cockpit to use the lav, a flight-attendant stood in the aisle but no-one entered the cockpit to replace the absent pilot.

A couple of years ago, I witnessed the same 'procedure' but without as much of the 'theater':
During a very smooth flight, the 'fasten seatbelts' lights went on, people got to their seats, and a couple of minutes later, while I was still wondering why we should secure ourselves in the seats mid-flight in perfect weather conditions, the cockpit door opened and a pilot went straight to the lavatory. Sure enough, shortly after he was back in the cockpit, the seatbelt lights turned off.
I thought of it as a rather elegant, unspectacular way to make sure the restrooms are vacant before the pilot leaves the cockpit. I pictured the alternative of the pilot having to stand in front of the lavatory door, waiting for 10 minutes for the old lady to fix her make-up, and concluded that I prefer the pilot to be in the cockpit instead of standing there waiting for the lavatory to become vacant.

Airlines are free to add any safety procedures they deem necessary for safety-of-flight situations. If that is what they did, it's likely standard procedure for that airline.

Crews usually work together for several days as a unit, and the CA and FO usually alternate flying each leg. This allows each to stay current and for the FO's skills to grow through critique by the CA and by observing the CA, depending on whose leg it is. In the event of emergency, though, the CA will usually take over.
Part of the reason the FO is there is to handle things if the CA is somehow incapacitated, so he is necessarily fully qualified to fly the plane alone. However, for security and safety reasons, both pilots are required to remain in the cockpit except during brief periods during cruise, such as the one you describe.
It is remotely possible that it was the FO's first revenue flight in type; after all, everyone has a first day at any new job. But there is nothing in your story that would indicate that was true in this case. It just sounds like the CA needed to use the restroom, nothing more complicated than that.

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Can a pilot tell a controller they don't need IFR clearance?
A pilot requests a zone transit. The controller asks if they can accept IFR clearance, they cannot, due to lack of a rating or equipment. But the weather doesn't require IFR, i.e. visibility is 10km+ and few clouds.
Why would a controller do this and can the pilot assert that they do not need IFR? (I heard of this situation happening recently)

Can a pilot tell a controller they don't need IFR clearance?

This is backward, you don't tell a controller what you don't need. You request what you do want and they'll usually do their best to accommodate, limited sometimes by controller workload.
The flight rules are passed on the controller's request to "pass your message" in the UK.
"[Station] Radar, G-ABCD request basic service and zone transit"
"G-ABCD, [Station] Radar squawk 4567 pass your message"
"Squawk 4567, G-ABCD is a [type], [Origin] to [Destination] **VFR**, 2,500ft QNH 1013, request zone transit north to south via your overhead"
"G-ABCD QNH 1014, basic service outside"
"QNH 1014, Basic service, G-ABCD"
....
"G-ABCD can you accept an IFR transit"

.. See below

Why would a controller do this

When someone flies VFR through controlled airspace they're a little bit of an "unknown" for the controller. They, by definition, will need to remain clear of cloud and will be responsible for maintaining separation from other VFR Traffic. There is, to a lesser extent, the appreciation that those pilots may well be slightly less accurate with their flying. All that together, leads controllers to allow a lot of leaway to those pilots. In some respect, it's a much higher workload for those ATCOs, as they need to expect the unexpected. (sidenote, in UK Class C airspace, the controller is responsible for separating VFR from IFR traffic - but for the same reasons as mentioned above they need to be extra careful with VFR traffic)
On the other hand, IFR traffic is expected to fly accurately and follow all instructions as professionally as possible within safety limits (pilots always have the final say!). IFR pilots wont suddenly change altitude nor direction due to a cloud and all IFR traffic will be under radar control.
All this together, what I suspect is that the controller you heard was under a high workload, and asked whether the pilot could accept IFR transit as this would not increase their workload significantly.
As with any such question, we can only speculate as to the controllers motivation for asking the question.

can the pilot assert that they do not need IFR

I don't think this is a "do you need" sort of request. The correct answer if the pilot is unqualified for IFR and the request "G-ABCD, can [you] accept IFR [transit]" would be "negative. G-ABCD"

VFR weather doesn't automatically entitle a pilot to fly VFR, and temporary IFR restrictions are a thing, usually the subject of a NOTAM.
Large parts of normally VFR airspace around Paris are likely to be IFR only in August for security surrounding the Olympics, for example.*
A pilot can request VFR under those circumstances, but if the controller only offers IFR then no amount of assertion is likely to have much effect, except, possibly, resulting in a chat with the regulatory authorities.
*Years ago I flew to a small airfield south-west of Paris, VFR, and no problem. A few months later I wanted to repeat the flight but found that the whole of Parisian airspace was closed to non-IFR traffic. The reason: Paris was chock full of international dignitaries in the city for the bicentennial celebrations. Fortunately I'd picked up the NOTAM and went to a different field.

Should the first line have read "VMC doesn't automatically entitle a pilot to fly VFR"? I didn't want to change your answer in case I misunderstood the meaning of your intent.

@Jamiec I suppose so, but I think my meaning is clear enough. If you think it's important go ahead and edit it.

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Why do my ears pop if the cabin is pressurized?
Simple question:
If a commercial airline cabin is pressurized, why do my ears pop as we ascend and descend? I was always told this was due to a change in pressure, but if the cabin and my body are at the same pressure, there should be no force causing my ears to pop.

Cabins are pressurized between 6000 and 8000 feet of altitude, until you reach these altitudes the pressure inside the aircraft is increasing or decreasing depending on if you are ascending or descending. The pressure must match the ambient pressure at your destination so they can open the door.

"if the cabin and my body are at the same pressure" - this is incorrect which leads to your confusion.  When the pressure outside your body changes, there are all kinds of cavities inside you which are at different pressures.  Almost nothing is "at the same pressure".  That's why the cabin pressure is changed slowly, to allow for equalisation.  It's also why a sudden decompression can be very painful.  People have suffered from all kinds of barotraumas.

The middle ear is like a VSI, it equalizes pressure... only after a lag time.

Here is an illustration of how cabin pressure changes during a typical commercial flight:
image source: http://aerosavvy.com/aircraft-pressurization/
Note how when the pressure outside the aircraft is changing, the pressure inside the aircraft is also changing, but not as much.
During the flight shown here, you would experience about the same pressure changes that you would in an unpressurized Piper Cub that only went to 7000 feet.

Not exactly the same as an unpressurized flight to 7000ft. The rate of change is much lower inside a pressurized cabin. An airliners typical vertical speed is around 1000-2500 feet per minute and the cabin pressure changes at approx 300fpm.

Good answer, but you should cite the source of the image.

@Sami: Absolutely correct for, say, an unpressurized 7000ft ASL test flight of a commercial passenger jet. Cabin pressure would follow the red line to 7000 and remain there until it met the red line at the right side of the diagram. -- But I was actually thinking of a typical flight in, say, a Piper J-3 cub, which climbs at about 350 to 400 fpm with 2 aboard.

@OSUZorba: I put the image source in the description but I forgot you need edit privilege to see it: http://aerosavvy.com/aircraft-pressurization/

Lower pressure means also less weight.

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Is it safe to wear earplugs in flight?
Speaking in terms of health for the ears and eardrums, would earplugs that form an airtight seal be dangerous to wear in flight due to cabin pressure changes? What about in the event of a rapid depressurization? And does it make a difference in which phase of flight they're first put on (before take off vs when in cruising altitude)?

Small planes: You don't want an airtight seal, you just want to block out noise, from the engine and prop mostly.  Noise cancelling headsets are great for that, they take out a lot of the low frequency rumbling kind of noise that becomes mentally tiring to listen to after a while, and leaves the higher frequency part of speech from your copilot, passengers, and ATC a lot easier to hear and understand.  Commercial jet passenger: same thing, noise cancelling headsets, but without microphones, quiets the jet engine noise some, improves audio book, music, inflight entertainment listenability.

For small planes, a normal set of aviation headphones (that is, with a boom mike that plug into your plane's radio jack) works great.  Noise cancelling ones, unless they've improved considerably since I last tried them, aren't much of an improvement over normal over-the-ear ones.

@jamesqf In my experience of survey flying in light aircraft, active noise cancelling headphones could make a massive difference and were the difference between ringing ears and a headache after a long flight or not. Relatively new Lightspeeds and Bose were the best, the ageing David Clarks were mostly terrible.

I wear earplugs all the time flying in both pressurized and unpressurized environments, and have done it for many years.  Air pressure changes have no noticeable effect when wearing foam earplugs as the interface between the foam and ear canal is not totally air tight.   The silicone flanged ones made for airline flying have a tiny bleed hole in them (flanged ones are way too uncomfortable for me though).
If anything, on an explosive decompression, the earplugs would help by delaying the escape of pressure on the outside of the eardrum while the pressure equalizes on the inside through the eustachian tubes, which can take a second or two if you have to work your jaw to open them.
Put them in whenever you want and take them out whenever you want.

How about silicone flanged ones not made for airline flying, with no bleed hole? Would those be dangerous?

Haven 't used them flying for a long time, but I think the small volume of air wouldn't be significant.  You'd feel some pressure perhaps, and would pull them out.  But you'd only feel the trapped pressure after the inner ear had equalized.  My guess is it would mitigate the effect of the instantaneous pressure drop on the outside, if anything, because during an explosive decomp you instantly end up with 8 psi in your inner ear pushing OUT on your eardrum until the air gets out.  Pressure being retained on the outside temporarily between the earplug and ear drum would mitigate the effect.

Emphatically yes, it is absolutely safe.
Before the advent of noise canceling headsets, all of my Air Force flying was with foam earplugs. I never heard a single caution of any adverse risk, whatsoever. ("Don't eat them," maybe.)
This was in both pressurized & unpressurized aircraft, including missions where we'd depressurize the cabin from 8,000' to mid/high teens for high altitude airdrops, and then repressurize afterwards. Earplugs were never, as far as I ever experienced or heard about, a cause of any discomfort.

DON'T PUT EARPLUGS IN YOUR NOSE / PUT THEM IN THERE / DO NOT PUT THEM IN THERE ("don't eat them" reminded me of the Marbles episode of the cartoon Home Movies https://youtu.be/xpz67hBIJwg )

@ErinAnne  Okay, probably a fair point... it wouldn't surprise me if, in all the Air Force tech orders throughout all history, a warning about not putting earplugs into noses made it into at least one.  Probably shouldn't underestimate the ability of those documents to cover even the most absurd possibilities.

I also wear earplugs while skydiving, both on the way up and down. I consider them mandatory part of the gear to avoid (further) damaging my ears and have never had any issues with them.


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Are there any airlines that fly a route that has an arrival time earlier than its departure time?
Imagine the scenario where an airline flys a short 30 minute route which crosses a timezone going west. They could theoretically leave at 00:15 (local) and arrive at 23:45 local the previous day. I'm wondering if there are any airlines which fly such a route.
P.S. I'm specifically interested in how the airline allows booking such a flight and the UI that is presented, but am leaving this question more general for any flights that do this.
P.P.S. If someone could help with the tags for this question, it'd be much appreciated.

hum, that's not very different from DST events happening twice a year.

https://travel.stackexchange.com/questions/14480/can-i-land-in-a-different-time-zone-before-my-take-off-time is basically the same question.

Looks like this isn't on topic for this Stack. Should be on travel instead. Sorry guys but thanks for the great answers!

UA892 leaves ICN at 6PM Friday (KT) and arrives at SFO at 11:30AM Friday (ET).
There's dozens of flights that leave Korea/Japan/etc and go to the US West Coast that arrive "before" they take off.
I'm not able to find a flight in these circumstances that leaves in the early AM from the west side of the Pacific, because that would seem to meet your criteria of arriving the previous day.  The same flight leaving at 6AM Friday would arrive 11:30PM Thursday.

I found such a route for you. KATL (Atlanta) to KHSV (Huntsville, AL) is a 57 minute hop from the Eastern time zone to the Central time zone. It appears how you would expect:

There used to be similar flights westbound into Chicago O'Hare, but it appears that United has padded the schedules a bit.  Presumably schedules are padded a bit more into the hub - for example Delta HSV-ATL appears to be scheduled for between 1:03 and 1:09.  There are some ATL-BHM (Birmingham, AL) flights that show the same effect.

Even better, Atlanta to Birmingham is only 47 minutes, so you can take off at 9:44AM and land at 9:31AM.

Back when Concorde was still a thing, British Airways' motto was 'Arrive before you leave', illustrating how you could arrive in North America sooner (in local time) than when you left Europe.

How does this not provide an answer to the question? It's no longer a current option, but it describes an example of such flights and shows that there's a long history of them.

The question says, "I'm wondering if there are any airlines which fly such a route." No airlines fly Concorde currently, so this doesn't provide a current answer to the question.

Yes, there are loads of these. My personal most frequent return flight - Atlanta to Nashville - is a good example. It's 35-40 minutes flying time, but moves from the Eastern time zone to Central, thus landing 20-25 minutes before it took off.
Much more extreme examples happen when you cross the International Date Line going East. For example, I've flown from Seoul (Incheon,) South Korea to San Francisco in about 10.5 hours. However, Seoul's time zone is 17 hours ahead of San Francisco's, so, despite the flight being 10.5 hours in duration, it landed 6.5 hours before it took off in local time.
Even flights with 14+ hour duration from East Asia to the U.S. mainland frequently land earlier than they take off.
The most extreme examples would be from an airport just on the Western side of the International Date Line to one just on the East side. These can land almost a full day before their departure in local time. In some cases, it's even possible to land slightly more than a full day before their departure, such as flights from the Line Islands of Kiribati (UTC+14) to, say, American Samoa (UTC-11).
And this is why aviation always uses Zulu time (UTC), not local time.

Yes, being a pretty frequent traveler between the US and Australia I've very often technically 'arrived' before I left. I tend to book through Orbitz and while the trip to Australia is often marked with a +2 to show that crossing the date line adds another day to your trip (ie, you leave on Monday and get there on Wednesday even though the flight is only 13 hours), when you return it's common to find flights that look like this one below. Where you leave Australia at 9:35am, fly for over 13 hours, and arrive three hours earlier:

Personally, I'm not a big fan of how Orbitz doesn't show the actual dates with the times. It'd help clear up confusion here.

I like JQ129 from Auckland (AKL) to Rarotonga (RAR). You arrive 19 hours before you depart.

Please don't refer to airports and airlines by just their IATA codes. Almost nobody will know what your answer means without Googling the abbreviations. You saved yourself maybe two seconds of typing and made everybody else spend at least ten times that much time finding out what you're saying.


text:
Is there a standard that defines all Special Service Requests?
I'm wondering if there's an international standard set of SSR codes. I see some references to IATA standardizing these, however, I can't find a reference to where IATA would publish these codes.

Just to be sure .. "SSR code" usually refers to a transponder code (secondary surveillance radar). Is this what you are talking about, or is it something else entirely?

@Hougaard see the question title. I'm referring to the special service request codes referring to passenger requests, such as special meal requests (LFML - low fat meal) or disabilities such as deafness (DEAF).

Possible duplicate of Where can I find an accurate list of IATA meal codes?

@fooot note that I'm asking whether there's a body who regulates all SSR codes. Not just those for food.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Do airplanes have sensors to detect landing gear fires?
Given that retracting a landing gear that happens to be on fire is a suicidally bad idea, for reasons that should be immediately obvious, do airplanes have temperature sensors on their landing gear in order to detect landing gear fires and prevent burning landing gear from being retracted?

Related: Is wheel well overheat detection (not brake temperature sensor) necessary for commercial jet aircraft?

There are fire detection heat sensing loops in the gear well.  If a gear was on fire it would trigger a "GEAR OVERHEAT" message and warning when the gear was up.  There are no retraction prevention systems that are able to detect fires at the gear.  Nationair was a unique series of clusterflarks leading to the accident, on top of the fact that the magnesium wheels started to burn.  Modern magnesium alloys don't do that.

By the time the flaming gear is in a position to trigger the GEAR OVERHEAT warning, it's already in close contact with the flammable hydraulic lines in the well, which will shortly ignite the fuel tanks above the well, and your aircraft is already doomed.

I added a line to cover the magnesium factor.  The DC-8 had old magnesium wheels and in those days they could catch fire if heated sufficiently (like scraping along pavement at 130 kt) and the resulting fire is intensely hot and can't be blown out.  This doesn't happen with modern alloys and a rubber fire wouldn't sustain itself at flying speed.  The bottom line is that the risk of a Nationair type event on modern aircraft is too microscopic to require mandating a system like that.


text:
Does heavy air pollution improve takeoff performance?
As you all probably know by now, aircraft have much better takeoff performance when and where the air is denser; this is why flights need to either use longer runways or jettison passengers and cargo on hot days (hot air is less dense than cold), and why a disproportionate number of the world’s longest runways are at high-altitude airports (air is much less dense at high altitudes than low).
Do aircraft see a similar performance boost at airports with heavily-polluted air, laden with dense gasses such as carbon dioxide, sulfur oxides, nitrogen dioxide, hydrogen chloride, nitric and sulfuric acids, and heavy hydrocarbons, plus lots of soot and tar particulates which raise the air’s mass much more than they do its volume?  Or is the benefit of having denser air swamped by the engine-performance penalty of having air with a lower oxygen concentration (a considerable quantity of said oxygen having gone into the formation of many of the aforementioned dense gasses)?

That pollution is measured in parts per million. for example CO2 is only 380 ppm

Percentages of pollutants will not have a significant effect on earth as compared with temperature and pressure.  However, on a planet like Mars, with a CO2 atmosphere, the density difference may be significant enough to effect lift calculations.
Maybe NASA could go with a twisted Prandtl biplane using a high altitude electric motor and prop.  They have reached 95,000 feet on earth with Helios, but had issues with structural strength.

"Maybe NASA could go with a twisted Prandtl biplane using a high altitude electric motor and prop": On Mars atmosphere density is very very low (1% of Earth), that's why lander don't land on parachute, but on retrorockets.


text:
Why does the B-52 have such a tiny rudder?
The B-52 (aka Stratofortress, aka Grey Lady, aka BUFF) has a minuscule rudder for an aircraft of its size and wing-mounted engine placement:

Compare to, for instance, the rudder on a 747:

The B-52’s rudder is so small that it can’t be used to decrab the aircraft during a crosswind landing, meaning that it had to be designed to stay crabbed throughout the landing roll, forcing the designers to use a fully-steerable dual-bicycle landing gear layout (plus wingtip outrigger gears that are there solely to keep it from tipping over) instead of the conventional tricycle arrangement.
Why, then, did the B-52’s designers give it such a small rudder?  One could argue that, because it has four engines on each side, rather than one or two or three, it doesn’t need a large rudder, because the thrust differential (and, thus, yawing moment) in the event of an engine failure would be minimal).  However, if you look more closely, that argument doesn’t hold up, because the B-52’s eight engines are mounted in conjoined pods, two engines per pylon, which virtually guarantees that an engine failure will also take out the engine right next to it;1 thus, one would expect that the design case for the B-52’s rudder would be a double engine failure of both engines on one pylon, rather than the improbable case of one engine failing and somehow managing to leave the one next to it completely intact.  So why isn’t the B-52’s rudder bigger?

1: For instance, the danger of cascading engine failures is one of the main reasons why no airliner designed after 1960 has ever used conjoined engine pods.

It's possible to fly one without a tail at all although 3 days after that another B-52 crashed after the tail separated. If the tail were any bigger, it would come off easier.

I would suggest that while the small rudder may have driven the choice to have crosswind landing gear, the choice to have crosswind landing gear did not drive the choice of the "bicycle" arrangement plus outriggers.  The B-47 used the same.  It is a natural result of the choice of the high wing configuration, to allow a large bombload to be carried near the CG.  There's no inherent reason why a tricycle-style landing gear can't be adapted for crosswind gear as well.

There are two reasons and they date back to the early designs for the aircraft. Keep in mind the tail is different now than when it was originally designed. Boeing has originally planned for an all moving vertical stabilizer but engineers doubted its reliability and the systems to operate it simply would not fit in the tail at the time. More importantly the original designs had sufficiently larger control tabs but this lead to an elevators and a rudder that had a lower critical mach number than the wing (i.e. the empennage would stall first). The engineers shortened everything to create a more stable situation as is noted in this passage:

Concerning the rudder, the situation is much worse. The B-52 rudder
  and elevator have an exceptionally narrow chord. Most airplanes have
  at least a 25% chord, which allows sufficient power and effectiveness
  in both yaw and pitch during takeoff, landing, and asymmetric
  conditions. The same is not true of the B-52 with its 10% chord rudder
  and elevator. The chord was reduced because original designs of the
  aircraft had the tail exceeding critical Mach prior to the wing. The
  chord of the tail was reduced to ensure that the wing reached critical
  Mach first.[15]
The original designers knew that the rudder was underpowered. An
  aircraft the size of the B‑52 requires a massive rudder that does not
  exist. This rudder is insufficient for the basic needs of the
  aircraft, let alone for asymmetric engine-out scenarios. Original
  plans called for an all moving vertical tail, the first of its kind.
  However, Boeing doubted the reliability of the hydraulic actuators
  necessary to achieve this. The design was also too heavy for the tail
  structure to sustain. Therefore, Boeing designed, built, and
  incorporated the yaw-adjustable cross-wind landing gear,[16] what is
  known to B‑52 aviators as ‘cross-wind crab.’ This system allows the
  B-52 to operate during normal conditions of take-off and landing in
  crosswinds. However, the true problem was asymmetry.

Several factors come into play:

Having 8 of them, asymmetric thrust after an engine failure - which is often the dimensioning case for the size of the vertical stabilizer - is not much of a problem.
Lateral control is primarily maintained by operation of spoilers.

Apparently, an all movable vertical tail was to be used but didn't make it because of doubts about the reliability of hydraulic actuators.

This makes me wonder a couple of things. One, if lateral control is primarily accomplished using spoilers, why is there a rudder at all; and two, given that there is a rudder, what are the advantages to making it small?

@TannerSwett Good question. I can only guess that the decision to drop the all-movable rudder happened at a late design stage, when the the small rudder already existed

Except that, due to the B-52's engine arrangement, a failure of one engine is likely to also take out the engine next to it on the pylon, meaning that you've now lost half the thrust on that side, rather than just one-quarter.

@TannerSwett: The spoilerons provide lateral (roll) control.  The rudder provides directional (yaw) control.

I have a vague recollection that the entire empennage was reduced in size due to the introduction of computer-control of stability and manoeuvrability.  The monitoring/ detection of and response to out-of datum attitudes meant that large control inputs were no longer required. I think this lead to a weight saving in the order of several tons. The concept had a fancy name- something like Control Configured Vehicle.
If this is not totally correct- apologies; I'm recalling stuff from 50 years ago.
Not many large aircraft have direct physical connection between inputs and outputs, even considering hydraulic, pneumatic or electric servo actuation.  Pilots request a function and the computers rationalise and deliver the signals to the functions.

CCVs were researched in the 1970s. But maybe the addition of a yaw damper is what you meant?


text:
How can I communicate an emergency de-pressurization descent to the cabin as a passenger?
Hypothetical scenario. I'm on a commercial airliner (A320) as a passenger, sitting by the wings. We are cruising at 32,000. The oxygen masks suddenly drop down and the nose pitches down heavily, whilst banking 30 to 45 degrees to maintain positive load factors.
Obviously everyone is panicking, I fit my oxygen mask and realize what is happening. We likely lost cabin pressure and are descending to a safe altitude. In a few minutes, we'll be at 10,000 and can safely remove the masks and land at the nearest airport.
I want to communicate this to the rest of the passengers, to make them feel at ease and less panicked. Obviously the cabin crew are busy helping children and others fir their masks, so don't have time to communicate this, the pilots are also far too pre-occupied.
How can I best do this? Could I take a deep breath with the mask on, remove it to explain what is happening at high volume and then pause for breaths with the mask on? Or maybe I could write it down and pass it around on some paper / a phone?
Any advice would be much appreciated.

Several answers, all upvoted. If down-voting, please explain why or edit the question.

I think the answers explain quite well why people might downvote such a question. from the downvote tooltip: "this question does not show any research effort; it is unclear or it is not useful"

@Federico what kind of research would answer the question Cloud made, please explain. The question is chrystal clear, at least I have no trouble understanding it, and I see great opportunity to advance and promote safe passenger behaviour and understanding of emergy situations here. Absolutely no reason for downvotes IMO.

@Jpe61 OP has asked several questions like "how can I do what a pilot/other crewmember is tasked with doing, as a passenger?" he should read/remember the answers and comments to those questions, because the answer is always the same.

Downvoting because this is an even more ridiculous question than "what happens if the flight crew are incapacitated and I have to fly the plane".

If the question is a dupe, it should be voted to be closed as one. And this might not be the most mature questions here, but ridiculous?

I’ve been a passenger on a plane in an emergency depressurization.
The first thing to realize is that everything happens amazingly fast. Even as a (GA) pilot myself, it was almost over before I even realized what was happening.
The second is that pretty much everyone on the plane grabbed their masks and started putting them on as soon as they dropped, then started helping others, exactly as directed in the briefing. Keep in mind that roughly half of passengers are frequent fliers who have heard that briefing hundreds or thousands of times. My mask was on before I had time to think about why I was putting it on.
Third, as soon as the cabin crew had their masks on (which took longer than me since they had to get back to their seats), they made an announcement for everyone to put on their masks. And one of the pilots broke in over that announcement with his own announcement saying the same thing. The cabin crew did not assist passengers, nor were they “busy” with anything else. There was nothing else they could do.
All that happened in the first fifteen seconds or so. That is why crews drill on emergency procedures over and over until recognizing and responding to emergencies is a reflex.
Lastly, as we continued the descent, I was trapped in place by my seatbelt and mask, and the plane was tilted so sharply that I couldn’t have moved much anyway. I assume that’s why the cabin crew stayed in their seats too. The general noise level was so high that, even if I screamed (as a few other people had started to do) at the top of my lungs, nobody else could have understood me anyway.
Maybe two minutes later, we leveled off, removed our masks, and continued on to our destination. Aside from the masks hanging down, it was a totally uneventful flight after that. Drink and snack services resumed, there was a line for the toilets, and people went back to their movies or books or naps like nothing had happened. Maybe liquor/wine sales were a bit higher than usual.

A couple of things that get drilled into you in first aid or emergency response training is 'if you aren't part of the solution you're part of the problem', second is 'don't become a casualty.' In other words, don't be a hero. In the scenario you describe there's going to be yelling and screaming from all around, raising your voice isn't going to help the situation. Why would they listen to some random person who stands up and starts shouting anyway? I haven't been in an emergency descent but I've been in my fair share of crises, and I guarantee that no matter how amazingly composed you expect yourself to be you will be crapping your pants like everyone else, don't assume you'd be the calm voice of reason. So:

Put your own mask on first so you stay conscious, and aren't part of the problem
Help others put on their masks after you put on yours, so you are part of the solution
Sit down, keep quiet and listen to instructions, so you aren't part of the problem

Lead by example by maintaining calm, assist others where you can without getting in the way, listen to instructions and stay out of the way. If you want to communicate give a confident thumbs up to people to let them know you're not worried.

Best thing you can do is remain calm, and let the trained personnel handle the situation.
Panic is a state of mind impenetrable to reason, and you being a random person amongst passengers will absolutely not help in communicating with your peers. One of the major reasons for crew wearing uniforms is that it gives them authority. This helps them control the crowd in difficult situations. Imagine the purser shouting out commands wearing a worn out t-shirt. Nope...
So:

Do not interfere
Be calm
Do not write and pass on messages, they are a distraction at best

You may try to reassure people directly next to you, but do not talk over crew announcements.
Whatever you do, do not:

Remove mask untill told so
Unbuckle your seatbelt
Shout even the most soothing words


text:
How does the emergency frequency work?
When I'm flying from my airfield, I usually am out of range of the airfield's radio within 50 miles or so, at low altitudes. How does the emergency frequency (121.50) work? Where is the location of the tower and how do you speak to someone if you're not in range of it?

This might be country dependent. Wikipedia says, "In the United States, the emergency frequency is monitored by most air traffic control towers, FSS services, national air traffic control centers, military air defense and other flight and emergency services, as well as by many commercial aircraft. The notice to airmen FDC 4/4386 requires '…all aircraft operating in United States National Airspace, if capable, shall maintain a listening watch on VHF GUARD 121.5 or UHF 243.0.'"

all aircraft operating in United States National Airspace, if capable, shall maintain a listening watch on VHF GUARD 121.5 or UHF 243.0 - Yea that doesn't happen. People are busy flying

"People are busy flying": most of them.

Note: other pilots may relay your emergency. Other SAR services may monitor the frequency (previously 121.50 was also used for general emergencies, e.g. in mountains). -- I do not think there are many non-oceanic areas without coverage (UHF should have long range).

@cloud airliners typically monitor guard. Some GA pilots do.

Older analog ELTs on 121.5 seem to get noticed pretty quickly. Except, of course, in remote areas with limited over flights.

As a point of information: while I can't always hear the chatter from stationary planes at the local airfield, once they're airborne I can hear them to about 30 miles out. There's lots of small-to-medium fields within that radius, not to mention Gatwick, and these days a receiver that can sound an alert when there's traffic on a specified frequency is a trivial investment.

@mins: See also.

You're out of range of you airfield radio operator on the frequency they are tuned, but you almost certainly not out of range of all radio operators.
In the UK, there are military units, LARS, area controllers and towers at bigger airfields as well as all the commercial airliners all tuned to 121.50.
As wikipedia says:

In the UK, 121.5 MHz is monitored by the Royal Air Force Distress and Diversion cells (known as "D&D") at the London Terminal Control Centre and the Shanwick Oceanic Control, from a nationwide network of antennas. Depending on the aircraft's altitude and location, the personnel in the centres may be able to use triangulation to determine its exact position which can be useful to the pilot if the aircraft is lost or "temporarily unsure of position".

So there you have it, there are a network of antennas which will cover you wherever you are.

You can also do a practice pan on 121.5 I recommend everybody do this once - the relay delay took me by surprise, but they were able to triangulate me and give me a vector. Interesting to do

Just occasionally others listen to 121.5 MHz too. The nuclear Larmor frequency of the 31P nucleus is ~121.5 MHz when placed in a 7T superconducting NMR or MRI system. I am an academic and when working on such a system we one-day had a huge "noise" peak that did not come from the experiment. A bit of debugging later and this peak persisted even when the coil ("antenna") was outside of the magnet and indeed the cable was not connected to anything. A bit of debugging later and it turned out to be a SAR helicopter on the hospital pad blasting RF that I was receiving part of despite trying not to!

@Landak other wordly?! ;d

Besides pretty much every ATC ground station, on airliners, with 2 Comm radios, normally Comm 1 is used for all ATC 2-way communications, and Comm 2 for ATIS, talking to Company ops, possibly air-to-air, etc. When not used for that sort of stuff, it's normally set to Guard (121.5), esp over sparsely settled areas or areas adjacent to or in the middle of oceans.
So in your case, airliners on arrivals and departures probably won't be, but those passing overhead UK to or from the North Atlantic Tracks will probably have Comm 2 set to 121.5 and if you broadcast a Mayday, one is likely to answer if in range.
I once arranged rescue, after being forced down by engine trouble on a random lake in the Canadian wilderness, by raising an airliner on Guard with a PAN call when I saw its contrail overhead.

At airports with a control tower, the antennas are located on the airport—on top of the control tower itself or on a dedicated (and relatively short) radio mast elsewhere on the field. As you have found, control tower equipment is not designed for long-range communication. It doesn't need to be.
The trick with the emergency frequency is that it is the same everywhere. Usually the authorities try very hard to assign radio frequencies for various ATC units and functions to ensure that transmissions from pilots will not be received by more than one ATC unit, and if there are problems a new frequency will be assigned instead. The Guard frequency is exactly opposite: every ATC unit which monitors Guard monitors and can transmit on the same exact frequency, 121.5. This means Guard is not ideal for routine communication—every time you transmit you will be coming out of speakers in several different buildings, only one of which needs to be hearing you—but perfect for emergency communication, when you need to talk to somebody, anybody, right now.
Radar control facilities often cover far more airspace than can be reached by a single antenna site, so they will have remote antenna locations and audio signals will be carried back and forth along telephone wire or similar methods between the remote antenna and the control building. When necessary to ensure coverage, an antenna dedicated to 121.5 will be included at the remote site.


text:
Is it safer to fly over 3,000ft for General Aviation?
I have been reading over the UK Airprox annual report of 2021 and it states:

In 2021 – 76% of all events and 83% of all aircraft-to-aircraft events took place at
or below 3000ft altitude.

In 2021 – 76% of all events and 95% of all aircraft-to-aircraft events took place in Class G Airspace

In 2021 – 21 out of 22 Category A aircraft-to-aircraft Airprox involved GA Sports
and Recreational light aircraft.

Now as someone that spends 90% of their flying time in Class G airspace, below 3,000ft (because higher than that phone signal doesn't work, which means I lose Skydemon and SafeSky on my tablet) in light aircraft, this concerns me.
My question: Would  it be safer to fly over 3,000ft, which would sacrifice use of the Safesky app and navigation aids, rather than use these apps but below the altitude in which 83% of near misses occur?
I am aware I could buy a sky echo device or similar, but they are expensive and cumbersome. Also, most air prox incidents actually involved both aircraft having detection equipment installed and active anyway.

Hypothetically, if 'only' 100-83=17% of accidents take place above 3kft, but only 10% of GA flights are above 3kft, that would make flight above 3kft more dangerous. That is to say, these statistics are meaningless on their own. Another example: maybe (probably?) most airproxes are in the traffic pattern of airports, so then your cross country altitude doesn't factor into safety at all.

Here's another statistic, about 75% of my flying time is under the LTMA which has a floor of 2500ft :( I'd love to fly above 3kft

@Jamiec why don't you?

@Cloud Because the LTMA is class A. With the 200ft guidance that means I stay well below 2300ft for much of the time out of necessity

@Cloud, from your body content, it looks like you're specifically asking about mid-airs, but your general title is about all GA. Could you define "safer"? It might make it easier to get you a salient response to your question, so we can distinguish between sampling bias (many (most?) GA pilots cruise below 3k, and all pilots fly below 3k' at some point in their flight) vs. the safety metric you're concerned about.

"There are lies, damn lies, and statistics." - Mark Twain.

Most GA mid-airs (maybe nearly all) are airplanes on convergent tracks roughly in the same direction. Such situations happen where airplanes converge either near airports, or around landmarks that are popular sight seeing spots (which can be even worse because airplanes converge and hang around for extended periods, and pilots generally aren't making position calls).
So the risks are more geographical than altitude related, and the most dangerous phase of flight is usually approaching the airport and in the circuit.
That being said, in general, "altitude is life" in the same vein that speed is life, in that you have more options when something goes wrong, and as far as running into people goes, the "Big Sky" concept of collision probability moves in your favour. Fewer micro/ultralights and paramotors etc.
For example, if I'm cruising somewhere at 1500 or 2000 ft, in addition to watching for paramotors and geese, I'm scanning for landable areas all the time. Less so above 3000. So in general, higher is safer all around (unless you caught fire I suppose).
Problem with systems like SafeSky and FLARM is they only work on targets equipped with transponders, and lots of aircraft aren't. They need to be treated like the passenger who sees something and taps you on the shoulder. Useful, but not something to rely on to keep you alive, and you need to act like they're not there even when they are.

Thanks John, I do wonder - why don't the CAA just make transponders a legal requirement?

Transponders require an electrical system, or a large battery to operate @Cloud. They add weight as well, so your gliders and ultralights aren't going to be able to carry them. Plus, they aren't some magic safety bullet, your best safety system is the mk1 eyeball and your neck on a swivel.

+1 for the sentence alone Useful, but not something to rely on to keep you alive, and you need to act like they're not there even when they are.

@Cloud apart from technical reasons, some mentioned by GdD, there is also a costs aspect. I think a certified transponder/ads-b transmitter + certified gps + installation starts at above 2500 EUR/USD/GPB. For the lower end of the aviation spectrum (e.g. a motorised paraglider) that is significant part of the total costs of the equipment, including the aircraft.

@Cloud, additionally, there's the problem of relying on a technological solution as there has to be a way to handle when the tech breaks down. On a huge, distributed scale, a certain percentage will always be dysfunctional, and being able to provide guarantees gets  tricky. Do you ban all flights from non-functional entities? How do you ensure they are functional, both before flight and during? The ADSB mandate already shows much of the problems of a mandatory peer-to-peer roll-out, and ADSB isn't even intended to provide collision avoidance (https://aviation.stackexchange.com/a/100188/20394).

@Cloud You already have to have an encoding transponder to fly in transponder airspace. In uncontrolled airspace, such a mandate would just drive more people out of aviation, with not all that much benefit, because mid airs are not that common. One here, one there, well within the calculated risk balance consideration you take when you do a  "dangerous" activity like flying.

Given the choice of:

more altitude and no electronic conspicuity
less altitude and electronic conspicuity

I would take option 1 any day over option 2. Get your eyes outside the cockpit, have everyone on board do the same. There is no substitute for a good lookout. The EC device does not and never will pick up all traffic.
The time when you might benefit most from having that EC device working is when you're approaching and in the circuit, and then you are at a lower altitude anyway. Your statistic:

76% of all events and 83% of all aircraft-to-aircraft events took place at or below 3000ft altitude.

Will be because, as we know, most incidents happen around busy areas like the ATZ.


text:
Can ATC tell someone to leave the airspace because they called them by the wrong name?
I will preface this question by saying that the story in question is anecdotal, told by an instructor at an airfield I was visiting. I will obfuscate the callsigns and airfield in question.
Apparently, a pilot got onto the frequency and said:
"[Airfield name] Traffic, [callsign]"
[Airfield name] ATC responded with:
"I've been to University for 8 years and have several million pounds of equipment here, I'm not just some guy with a walkie talkie, please turn around"
He proceeded to leave the airspace and diverted to a different airfield, however, if he didn't, what would be the potential repercussions? I'll add this was a  VFR flight with no flight plan.

What class of airspace was this airfield in?

It's a CTR within an AIAA. I'm not sure what class that makes it

@Cloud Civil CTRs are class C or D

Assuming the ATC response is embellished a little bit in the retelling, what probably happened is a pilot entered controlled airspace, or was about to enter, without a clearance, thinking the airport was uncontrolled (addressing the frequency as "traffic", which is just addressing other aircraft in the vicinity, tells you that).
The controller was doing the pilot a favour by telling him to turn around, and the controller's statement suggests he/she wasn't too pissed off just yet. If the pilot was already inside the positive control zone, the controller could have busted the pilot for entering without a clearance.
If you look up aviation regulation enforcement action summaries for your authority, blundering into positive control airspace without a clearance is one of the more common infractions.
Something like that might bring down a fine, say 500 or 1000 dollars, (or quid) and possibly a license suspension for a few months, as you are brought before an administrative judge or tribunal.

Or he just wanted this clearly confused pilot off his back—busting the pilot would require still guiding the plane to landing and then dealing with the violation.

Yes. Before the person has got to the point of endangering someone, better that to avoid the paperwork.

Thinking about it more, big class Bravo airports are a scary thing for most low time VFR pilots, so it probably was a class D, likely newly towered. So now there is this confused pilot approaching. The response by the book would be something like [callsign], stay clear of delta, say position and altitude, [airport] tower — at this point tower does not even know where the plane is, because it's squawking VFR if at all. But the pilot seems not to know about the delta, so it would just confuse them and trigger more back-and-forth. If the tower is busy, just turn them away is much easier.

Yeah.I tell new pilots a couple of tips to mellow them out.  The vocabulary used nearly all the time is quite small.  Maybe, 50 words?  Memorize all the common phrases and words in advance.  The other one is simply to listen in on LiveATC.net every evening when sitting around chilling, to simply get used to the way they talk.

Somewhat pedantically, but technically if you address a station as "[Airfield] Traffic" then you're not not communicating with any sort of air traffic officer, you're addressing other pilots on frequency.
If there happened to be an ATCO on duty at said airfield, they would simply reply back along the lines of "G-ABCD this is [Airfield] Radio....." or "G-ABCD this is [Airfield] Information....." as appropriate. This leaves full ATC - such as an approach/radar/tower controller - but the likelyhood of anyone calling Traffic on that frequency is vanishingly unlikely. And even if it did happen, the same would apply "G-ABCD, this is [Station] Approach/Radar/Tower".
An air/ground or Information controller has no jurisdiction over aircraft in the air - the worst they could do is file a report about you busting their ATZ without establishing 2 way communication. They might ask you to vacate the ATZ but they certainly couldn't compel you to.
What you describe is very unlikely to have ever happened.

If you'd like some links to the regs (instead of some guy on the internet said so) I'm more  than happy to look them up for you.

I agree that the way that is phrased is unprofessional and unhelpful. If that was said in that way I would expect there's a lot of dialogue missing, but even then it still sounds dubious.

I believe this was said on the radar frequency, but again, this is 3rd hand information...

I think just disregard. Put it this way, I have never heard anything but utmost professionalism from every radar controller I've ever spoken to in the UK. If I ever heard anything remotely like that, I would be making a report.


text:
Why can't commercial aircraft have a wing boundary layer suction system?
I've read that NASA's boundary layer suction system on the wings can reduce drag by removing the boundary layer through the suction holes. If this can reduce a lot of drag (hence improving fuel efficiency), then why can't the same idea be used in commercial aircraft?

What makes you think it can't be used? In aviation, as in many industries, many ideas are not implemented not because it can't be but because of costs, complexity, maintenance, weight...and other drawbacks.

Boundary layer suction systems have been considered for a very long time, since they provide significant advantages.
However, their main disadvantage, which has never been satisfactorily overcome, is their propensity to clog with dirt and biological matter. The maintenance costs to ensure the system is operational would outweigh the gains in aerodynamic efficiency.
Additionally, this is not the kind of system that could be left to its own devices (good if it works, fine if it doesn't); it would need to operate consistently because the critical angle of attack would depend on it.
Furthermore, this system would require power to operate the pumps, and it is not obvious that the efficiency gains would make up for the power requirements in all scenarios.

Boeing did implement a passive hybrid laminar flow control system using boundary layer suction for the 787-9 on the horizontal and vertical tails. The passive flow control implementation appears to apply US Patent No. 7,866,609B2, which does not require a pump.
There are many practical issues that prevent a flow control device and/or method from being used:

performance degradation due insect contamination, roughness, steps and gaps compromising any drag benefit, e.g., Krüger-type flaps are typically used for insect protection, so flow control devices would need to integrate with such high lift devices,
any use of mechanical pumps increases weight, lifetime costs due to maintenance, and a reliability risk if the implementation substantially affects stability and control characteristics,
high energy requirements, e.g., active flow control actuators tend to consume a lot of power, so considering the whole point is to save energy, there should be a net gain.


text:
How does the load factor vary when the aircraft pitches up/down?
I know that when an aircraft starts rolling, it's load factor increases. But can anybody explain how does load factor vary when the aircraft pitches up/down? Does it increase/decrease?

Think not about the rate of pitching but rather about the skyward or earthward curvature in the flight path (trajectory).  This curvature is an acceleration, and requires a force to make it happen.
G-load (i.e. load factor) is essentially just the aerodynamic force generated by the aircraft, divided by weight.
In straight-and-level flight the G-load is +1.
In the case where the aircraft is wings-level and in a level upright pitch attitude (not inverted), we can observe--
If the flight path is curving skyward, the G-load is greater than +1
If the flight path is curving earthward, the G-load is less than +1.  It may even be zero or negative.
This answer could be expanded to consider other flight attitudes.  Think about a loop.  At any instant in time, if the flight path is curving, some force is causing that. The main forces that could be contributing to this curvature are gravity, and the wings' lift force.  Of these two forces, only the latter one determines the G-loading, i.e. the load factor.  In the plane's own reference frame, an "upward" aerodynamic force (towards the canopy) creates a positive G-loading, and a "downward" aerodynamic force (toward the belly) creates a negative G-loading.
Knowing this, you can compute the G-load at any instant, as long as you know the aircraft's attitude in space, velocity, mass, and the radius of curvature of the flight path.
Starting from level upright flight, if you pull back on the stick or yoke, you'll feel heavier.  If you push forward on the stick or yoke, you'll feel lighter.
Note: this answer assumes we are measuring the G-force near the center of pitch rotation of the aircraft.  A pilot seated far forward of the center of pitch rotation will feel a greater increase in G-load when pitching up, and a greater shift toward a negative G-load when pitching down, than if he were seated at the center of pitch rotation.  The same is true of the load factor imposed on any part of the aircraft structure.


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How do aircraft batteries power the engine/APU?
I fail to understand how do batteries power up the jet engines/APU. Are they responsible for starting up the Ignition that ignites the air-fuel mixture? Or is there some other function which I'm missing out?

Think your answer is in here:https://aviation.stackexchange.com/questions/12852/how-are-apus-started

Yes battery power will supply both the APU's igniter system and its starter/generator (a single motor that switches to generator mode after start, similar to turboprops).  So you need the APU to start the engines (notwithstanding other bleed sources) but you need the battery to start the APU (or an external DC power source - the APU will be fed from a DC bus; whether the bus is being energized by a battery or a DC ground cart, the APU doesn't know or care).


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What's the minimum survivable mid-air collision altitude in a glider?
This weekend I had my first gliding experience in an ASK21. My first surprise was being given a parachute. The briefing was simple, if we have a mid air collision, unbuckle the belt harness, remove the canopy with the emergency release, jump out, then pull the chute.
Now, I've spent a fair bit of time flying around at a couple of thousand feet and know how little time it takes to get from there to the ground. I cannot imagine how all of the above could be achieved from the typical gliding altitude of 2,000 - 3,000ft. Especially as getting out could involve re-orienting yourself from an inverted or otherwise non-stable position.
So, what realistically would be the minimum altitude required to do all of this and survive? What statistics are there, if any on glider pilots bailing and what is the survivability from different altitudes?

Rob Davies bailed out of Big Beautiful Doll (a P-51) at Duxford in 2011 - "According to Davies, he was at about 500 feet, "at the time of decision-making."  "And by the time I got out and got the 'chute open I was down to 200 feet. "  There's a video of it on YouTube

Thanks @DaveGremlin - here is the link for others: https://www.youtube.com/watch?v=ygcaalz6IRA - what exactly happened there? Why couldn't he land it?

"the typical gliding altitude of 2,000 - 3,000ft"  --  as the posted answer has indicated, that altitude range is plenty for bailing out successfully.  But, many readers will be noting,  in many parts of the world the "typical" altitude for a glider on a good soaring day is much higher than that!

PS I personally know a glider pilot who has used his parachute, within the last ten years, talked to him just this weekend, the (open-class) glider broke up during attempted spin recovery after accidentally entering a spin during strong thermal turbulence. That's not typical, but it has happened. Sorry though I don't recall the altitude where he left the glider. Considering the part of the country and the time of year, it's very likely that portions of the flight were well over 10,000' AGL.

@quietflyer I should have said the typical tug altitude I guess

Are we considering ability to survive despite a partial opening, or only the official minimum height for the 'chute?

@Cloud the most likely place for a midair is approaching or in the circuit, with aircraft on converging paths. That goes for airplanes and gliders. Joining the downwind, or on the base leg. For gliders, the next most likely place is in a gaggle in a thermal, which is the main reason single seaters a designed to be flown with parachutes. When I'm out soaring I might join a two seat training glider (often they won't have parachutes) in a thermal but I'll leave if I find myself getting close to them, cognizant of the fact they are parachuteless.

@Cloud I just watched your video. Terrific!. I hope you stick with it and make it your sport. The first time you climb in a thermal all by yourself is a huge rush. That's when you're hooked. That yaw string should be farther back on the canopy, so it's in your peripheral vision all the time. For a power pilot the footwork is the hardest part to master and the string works the opposite way to a skid ball, where you "step on the ball". I would tell students "think of the yaw string as a rattle snake; step away from it". I was out last week in the club ASW24 for 4 hours. It's like meditation.

@JohnK Thanks John! :) Really enjoyed it, very different to flying the C42, which is what all of my hours are in currently. I must say, I got quite airsick, but hoping that dissipates with time. Will think about your advice with the yaw string too :)

@Cloud The airsickness is from turning a lot, and goes away. You might be in a position to become a tow pilot with the club at some point, depending on the club's power experience requirements. I do both. Towing gliders develops your power aircraft low speed handling skills to a very fine edge.

@Cloud,  The sequence you have been told is not the correct one in my opinion.
If you ever has to bail out, chances are you will have a lot of random G-forces, so if you are not firmly seated in the plane you may have trouble getting the hood off. The better sequence is:

Get rid of the hood (which can be difficult on some gliders)
Unbuckle the belt harnes
Get out of the plane (This can also be difficult if having G-forces against you)
Pull the chute

Minimum survivable mid-air collision altitude? 1 foot above ground level. Obviously, parachutes aren't going to be very helpful. ;)

I fly gliders regularly and wear a parachute most of the time, and am also an ex skydiver. Strong parachutes indicates the opening distance of an emergency parachute is 150-300 ft, and advises bailing out at no less than 500 ft to be sure of full inflation before reaching the ground (though you could probably get away with 400 ft or less if you didn't dawdle).
In any case, in a mid air in the circuit at 800 to 1000 ft, with a glider whose control is doubtful, it's bailout time for sure.
The psychological barrier to bailing out can be pretty strong, especially close to the ground, and especially if there is the prospect of maintaining control of the aircraft. At 500ft it's going to look like you are jumping off the roof of a building even though it's plenty of height margin (base jumpers jump from that height all the time).
I once witnessed a midair between two gliders at about 1300 ft near the field. One glider more or less blew up while its pilot was in minding his own business in a thermalling turn (two gliders in adjacent thermals lost track of each other) as its tail boom was chopped off by the wing of the other glider and it simply disintegrated into pieces. He found himself falling strapped to a part of the fuselage shell and one wing. Released the seat harness, dropped clear of the piece, pulled the ripcord, and floated to a safe landing (the wing and fuselage chunk autorotated to the ground nearby, like the World's Largest Maple Seed). Easy, because that was the only option available.
The other pilot had a section of leading edge crushed into the spar and was having control problems where he would stall and roll off, but would recover, repeat, recover, repeat. He went in descending circles rolling off and diving then levelling off again. He stayed with it until it was too late and eventually dived straight into the ground. It's likely that the fixation on maintaining control, combined with the scariness of an exit below 1000ft did him in, though he had ample opportunity to bail out.
In any case, at normal circuit altitude and above, not a problem. And really, if your glider's missing a wing, you're going to try it no matter how low you are.

This psychology of hoping to maintain control is why at my gliding school we were instructed that if we lose elevator control, it is technically possible to land safely by using the trimmer (our instructor did this once, in an emergency, but he has a lot of experience), but we are advised to bail out nevertheless, as it is extremely difficult to do so, and even more difficult for novices to realize how difficult it is, in the situation. (Yes, landing with the trimmer can be practiced, but in an actual emergency there are other factors and it's hard to estimate how much control we still have)

If the trim is by a tab like on a Blanik that can act as an external operating servo, and the elevator is free to move because the cable circuit is broken and the surface is loose, you'll be able to fly it perfectly well on trim.  Some jets with non hydraulic flight controls actually work that way (eg, DC-9, where the control column itself works a servo tab, not the elevator surface directly). If it's a bungee spring up in the cockpit somewhere applying tension to the stick for you, it probably won't be of use unless the control circuit is still intact. You'll know soon enough when you try it.

On that note -- of the difficulty in leaving a potentially controllable aircraft and feeling shame or fear of the destruction of the airframe -- the USAF has been training pilots since at least the 1980s that while the plane can be replaced, they cannot: don't delay the decision to eject. At least, according to this training film: https://www.youtube.com/watch?v=dyjYp6WT7ww


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Illegal flying - does anyone ever ask to see your license?
This video tells the story of a pilot who, according to government records:

[Committed] four counts of identity theft related to his use of the victim pilot’s passport and personally identifying information to fraudulently obtain the FAA credentials at issue.

At his plea hearing, [he] admitted that he stole the identity of the victim pilot, which he used to obtain certain FAA credentials.

These credentials permit a pilot to fly multi-engine aircraft, and have strict requirements for training, knowledge and experience.  [He] had never been issued these specific credentials, and a general pilot’s license he had previously been issued had been revoked by the FAA.

Initially I was surprised that he had gotten away with this so many times and for so long, but then I realized, that I have never, or ever seen anyone get asked to provide their pilot's license at an airport or airfield. Nor has anyone ever asked for certificates of airworthiness, tech logs, etc. (in General Aviation).
Does anyone ever ask to see your license or other paperwork in the GA world? If not, then really what stops pretty much anyone with the money buying a plane and flying it around, it seems that you only get caught if you crash (which obviously you WILL without training).

I think @Pondlife answered this in What are the consequences of flying GA without a license (certificate)?. Also there is a difference between no license and no valid license, you may have a license, but for another aircraft type/category/use.

@mins I've read that, it does touch on the subject, but doesn't really talk about frequency of stops / checks (if they happen at all).

I think it is like cars: (I think I never got my permit checked). If you have a permit and you can drive, low or no probability to be checked. But I assume if you to egregious errors driving (or flying) you may get noticed. So, after spending money to learn flight, why not doing the final check? (and also note: if you cause an accident, you risk to lose all you have: no insurance will pay for you, so it is all your pocket money). So: risk vs. benefits

Watching that video, it's more big government agency inadequacy (in this case FAA, but you can imagine it being many others) and the dangers of a well practiced conman than it is about license checking!

@Jamiec agree, it's shocking really how easy it has been for him! Like a modern day Abagnale :)

There's an old joke going around about "the FAA being 'so proud' to announce that 'finally after years of hard work and advocacy' they managed to get 50% of the pilots in Alaska licensed".  Pulling a plane over and checking a license is more involved than with cars. Pairs of fighter jets are expensive to operate. Ramp checks are a thing, but seemingly rare. Of course, someone could by flying off their "back 40" in Texas where I suspect ramp checks do not happen.

"does anybody...."  -> circa 1983 flying routine diplomatic support missions into Sandinista run Nicaragua, they always asked for our pilot licenses. The USAF does not issue a "license" to its pilots, nor the FAA. They knew that but liked their fun. Included in the harassment entertainment package was the hovering Hind helo gunship tracking us as we taxied to parking.

In North America at least, "Ramp Checks" are a thing, where some FAA or Transport Canada inspector could approach you ask to "zee your paperz", including personal license documents and aircraft documents.
This is more likely at busier airports than little country airstrips, but you can never be sure. If you are caught with missing documentation, you might get just a stern talking to if it's just something minor and the inspector likes you, or get some kind of administrative penalty like a fine, but it could include a license suspension if it is serious enough (like being caught with an invalid medical).
I assume random spot checks are also done in the UK. If I'm towing gliders, I may not leave the gliders waiting in line in the lurch just because I remembered I left my licence in the car and had to go fetch it, but I wouldn't go flying without everything in order for both plane and pilot anywhere else, including other small airports. You never know.
In the case of someone up to no good, the chance of getting caught in a spot check is a calculated risk you take as a fraud artist, and is probably fairly low. Off the top of my head, I can only think of one person I've known in the past who's been approached by an inspector while out and about.
Another important consideration. If there's an accident and any significant violation of the regulations are involved, your insurance company may have a get-out-of-jail-free card they can play to avoid paying out. For smarter pilots at least, this is a stronger motivation to play it straight than getting caught and dinged by an inspector.

Does anyone ever ask to see your license or other paperwork in the GA world?

Yes, absolutely.
For pilots, your license and medical will be checked at the point that you renew/revalidate any rating or endorsement on your license. So things like an SEP, or an IR rating renewal requires that the examiner signing this off check your paperwork.
For aircraft, the pilot is obliged to check paperwork (airworthiness certificate, insurance, maintenance schedule, etc) is in order before each and every flight.

If not, then really what stops pretty much anyone with the money buying a plane and flying it around, it seems that you only get caught if you crash

Wouldn't the same be true for motorcycles, cars, boats or just about anything that is traditionally "licensed". You only get in trouble for not having a license if you....get caught.

I'm not sure revalidation counts... you're not going to revalidate a fake license :D

"For aircraft, the pilot is obliged to check paperwork" If I'm flying my 172, I'm the pilot and I'm checking my own "paperwork" with a wink and a nod. I think the question is, "is anyone else going to ask to see my paperwork?". Of course, if I'm renting the aircraft, you'd think the owner/agent would want to do some validation, but if I own it?

Brings up a related but separate question: Do I need a valid pilot's license to buy a GA aircraft?

@FreeMan no, why would you? You can buy a 18 wheeler truck without a license to drive it, why would/should this be any different for an aircraft? It's just an asset, people buy them without ever flying it themselves.

That makes sense, @Jamiec. But I wasn't sure.


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What is being proposed for converting UK NPPLs to PPLs?
There has been a lot of talk this year (both in person at flying clubs, online and in the monthly "Microlight" magazine published in the UK) about the CAA reviewing the license structure in the UK.
Currently there is no formal upgrade path from NPPL to PPL and only 10 hours can be credited towards training.
However, the CAA apparently are reviewing this, with a view to make changes in 2025. However, I have no idea what the proposed changes / path will be and can't seem to find that information online.
What are the proposed changes and what would a path from NPPL to PPL look like?
I recently enquired about adding an SSEA rating to my NPPL(m) license and was told there is no point due to the forthcoming changes.

For a little background, in 2023 the UK CAA launched a 3 phase consultation on General Aviation Pilot Licensing & Training Simplification. Much of this seems to have stemmed from the request to simplify licensing following Brexit, which has left us with a somewhat two-tiered licensing scheme.
There are in effect two Sub-ICAO licenses available

LAPL
NPPL

The responses to the first phase of the consultation, asking broadly what GA pilots would like the changes to be can be viewed here: https://www.caa.co.uk/publication/pid/11991
It is the proposals of the second Phase of the consultation which may go some way to answering this question. This can be read in full here (for aeroplanes and microlights): https://consultations.caa.co.uk/ga/pilot-licensing-review-phase-2-aeroplanes/
Section 4.24 & 4.25 of CAP274A lays out the **proposal **for PPL upgrade from the Sub-ICAO license

PPL upgrade
4.24  The proposed upgrade path from the sub-ICAO licence to the ICAO PPL(A) would consist of:

Meet the ICAO Annex 1 requirements;
Training as required at an ATO or DTO;
PPL skills test; and
Theoretical knowledge exams in:
▪ Air law and operational procedures;
▪ Aircraft General Knowledge – covering airframe, instruments, electrical systems, emergency equipment and powerplant;
▪ Principles of flight;
▪ Performance; and
▪ Radio navigation.

4.25 The ICAO Annex 1 requirements consist of:

40 hours flight time as a pilot of aeroplanes, appropriate to the class rating sought; and
10 hours of solo flight time appropriate to the class rating sought, under the supervision of an authorized flight instructor, including 5 hours of solo cross-country flight time with at least one cross-country flight totalling not less than 270 km (150 NM) in the course of which full-stop landings at two different aerodromes shall be made.

None of this is set in stone yet, and we have to wait for Phase 3 to complete which will be implementing the new rules.

Thanks Jamie! Can I ask, why the duplicate exams? Air law for example is part of the NPPL and if you already have a radio license, why re-do a radio nav exam?

I'm afraid I couldn't answer that. It's a question for the CAA if and when they change the rules.

Just 1 more question Jamie, if these changes are approved, when will they take effect? Just wondering if it's worth holding out on the SSEA rating and doing this instead if it'll be soon (in the next year or so)

Also, I thought you were a member of the CAA, apologies

I am by no means affiliated with the CAA.